1. Field of the Invention
The present invention relates to sorbing coalescing technology.
2. Description of the Prior Art
In the recent past there have been several well documented instances of the inadvertent spillage of non-aqueous liquids causing both environmental, ecological and even toxicological problems for plant species, insects, wild life and even people. Examples of spilled liquids include oils and solvents, and a group of materials known as PCB's, which in addition to being pollutants are carcinogenic. Further, in many cases when the spilled liquid is a nonaqueous liquid which is not compatible with water, such as fuel oil and hydrocarbon solvents, in addition to the spilled liquid, aqueous emulsions are also often formed. For many of these liquids, methods of clean up including adsorption and coalescing steps are known, even for relatively difficult ones such as crude oil and toxic PCB's.
Patents in the prior art in some way involve a particulate material for adsorbing or coalescing a non-aqueous phase, typically crude oil or a derivative of it, such as gasoline, diesel fuel or lubricating oil. These patents utilise a wide range of adsorbents and/or coalescing agents, not all of which are clearly defined. They include: polyethylene; polypropylene; polyisocyanurate; polyurethane; shreds of solids loaded polyurethane foam; silane cross linked polyolefin; polymethyl methacrylate; shredded fibreglass; wool; cork; styrofoam; polyester and/or cotton.
Kozlowski, in U.S. Pat. No. 5,239,040 discloses a particulate reusable polyurethane adsorbents capable of adsorbing many spilled liquids, and from which the adsorbed liquid can be removed by the simple process of centrifugation. The main limitation on the use of the particulate adsorbents of that invention is the properties of the liquid spilled. Any liquid which would destroy or dissolve a polyurethane polymer cannot be recovered using the product described by Kozlowski.
Another difficulty with spilt non-aqueous liquids arises when water is present. A water immiscible liquid can be present in association with water in two quite different forms. At least a part of it will generally be present as a discrete second phase, which may be heavier or lighter than water. The remainder will generally be present as an emulsion, of at least some level of stability, and in which water can be either the continuous phase or the disperse phase. In both cases, there is also the difficulty that nearly all substances that appear to be immiscible with water, for example light hydrocarbons such as benzene, in fact are soluble in water to a small extent, often at a level of parts per million.
Until quite recently it was considered that the chemical structure of the material used in the adsorbent or coalescing agent powder (units) determined the adsorptive or coalescing characteristics of the adsorbent or coalescing agent. There are numerous patents in which polyurethane foam is stated to be essential. According to Kozlowski, in WO 02/20115, not only Kozlowski polyurethane foam as described in U.S. Pat. No. 5,239,040, but also other matrix materials, when fabricated into a body of high surface area material such as foam, if used under the correct conditions, will function as an emulsion breaker, and will separate a flow of an aqueous emulsion into two separate phases.
Patents of the prior art use polyethylene, and describe comminuting a matrix material, typically a body of polymer foam, into small particles.